1. Field of the Invention
The invention relates to float switches and more specifically, the invention relates to float switches which open and close an electrical circuit in response to a vertical switch installed in the discharge line from a sump pump.
2. Discussion of the Prior Art
Many different types of float switches have been developed for opening and closing an electrical circuit in response to the level of a liquid within a reservoir. Generically, float switches include a floating buoy and a means, responsive to the vertical position of the buoy, for alternately closing an electrical circuit when the float achieves a predetermined maximum height and opening the electrical circuit when the float achieves a predefined minimum height, normally open, or normally closed.
One type of available float switch is taught by U.S. Pat. No. 4,001,533 to Conery et al, which includes a sealed level control switch for sump pumps operated by a pair of weights operatively connected to the control which has a sealed nonmagnetic material housing having a downwardly open recess extending thereinto from its lower surface. A normally open microswitch having a spring control arm extending therefrom and movable downwardly to close the switch. U.S. Pat. No. 4,084,073 to Keener discloses a float type control switch having a housing, a switch in the housing and with the switch having a spring control member extending therefrom to turn the switch on and off with movement of such control member, leads connecting to the switch and extending from the housing to the power controlled circuit. An activator arm is pivotally positioned in the housing for gravity actuated pivotal movement towards and away from the switch for engaging and moving the control member to switch closed position and to release it for switch opening action.
U.S. Pat. No. 4,746,776 to Komaniak discloses a float actuated switching assembly having a pusher linked to a float, a movable carrier member, preferably a pivotable cam, having upper and lower brackets between which the pusher moves, first and second stops to limit carrier movement, a contact member on the carrier positioned to contact the stops, and magnets to releasably hold the contact against a stop as the pusher moves toward and applies initial force to one of the brackets.
U.S. Pat. No. 5,297,939 to Orth et al discloses an automatic control for bilge and sump pump comprising a permanent magnet mounted in a float that is contained within a float chamber and which has a bottom opening through which the liquid can enter the float chamber. A top portion of the float chamber is provided with a one-way valve so as to allow air to escape from the float chamber, but which prevents air from entering the float chamber such that when the float moves up with the liquid, the magnet actuates a magnetic responsive switch such as a reed switch to cause the motor to drive the pump. When the liquid level falls to the bottom of the float chamber, air rushes into the chamber and allows the retained liquid within the float chamber to fall out the bottom and the magnet bearing float falls to the bottom, which turns off the pump motor.
U.S. Pat. No. 5,562,423 to Orth et al is an improvement over (939) having a float switch which is not physically directly attached to the motor housing. This patent has two chambers, one in which a magnetically responsive reed switch is mounted and the other chamber comprises a float chamber into which water is received so that as the water rises, the float rises in the float chamber. A magnet is carried by the float, which actuates the reed switch when the float reaches a predetermined level in the float chamber.
Another type of available float switches is known as a mercury-actuated switch. Mercury-actuated float switches provide superior switching performance, however, because of environmental concerns relating to the use of mercury, alternatives to the mercury-actuated switch are being explored.
In the submersible sump pump industry there is a need for a switch to start and stop a pump, when the pump is contained in a small pump. This switch must operate in a very limited space and not swing outward like a float switch. An example of such a switch is U.S. Pat. No. 5,155,311 vertical switch. This switch works well, but is limited in its on and off differential of 1" to 8". There is a great need for a vertical switch with a larger on and off differential. The flow control vertical switch of this invention fills this need since it has an on and off differential of two inches to over twenty feet.